Field of Invention
The present invention relates to a method of forming a cell structure, and more particularly to a method of forming a bifacial solar cell structure.
Description of Prior Art
Conventionally, when a bifacial solar cell structure is manufactured, an N+ region diffusion, e.g. employing phosphorus oxychloride (POCl3) as a liquid phosphorus source for the diffusion procedure, on a rear side of the bifacial solar cell structure is performed after an anti-reflection coating (ARC) layer, e.g. material composed of silicon nitride (SiNx), is formed on an upper surface of the bifacial solar cell structure. However, phosphoric acid removes a portion of the SiNx layer at a higher etching rate, and further the etching rate is considerably raised with the increment of the manufacturing process temperature. Thus, after performing the N+ region diffusion on a rear side, some pin holes are disadvantageously formed by the phosphoric acid in the ARC layer on the upper surface of bifacial solar cell structure, which causes defects to be formed on the surface of ARC layer on the upper surface of the bifacial solar cell structure.
Furthermore, it is required to perform an electrical isolation procedure for integrating a unit in a manufacturing process of the bifacial solar cells by using a wet chemical etching, laser isolation or any other methods in the prior art. However, all the aforementioned methods require at least one extra process step of the bifacial solar cell manufacturing flow to perform and attain the electrical isolation. Therefore, it is inevitable to increase the whole process cost and decrease the yield due to the at least one extra process step.
Consequently, there is a need to develop a novel method of forming a bifacial solar cell structure.